This is Thomas Mayer's blog about vacuum tube audio, to share updates about new amplifiers and preamplifiers and ELROG vacuum tubes.

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Thursday, April 12, 2012

The Modular Preamplifier, Part 9 : 10Y Linestage Chassis Design

Hi!

The two different linestages of the modular preamp concept did not progress as I would have liked. I hope to show the completed preamps soon. In the meantime I got the wooden frames for the 10Y linestage which differs from the other modules since it has the tubes, transformers and caps on top of the chassis.

Here some pictures of the chassis concept. The inside is still empty and needs to be wired up.

This one is quite tricky to assemble since no screws extend to the top or front. There are quite a few parts which have to go inside: Two chokes for B+, two filament chokes and input transformers.

The volume control at the right for 24 2dB steps from the Tribute lineout / volume control transformers. The linestage has 4 inputs. Two regular high impedance inputs for all kinds of sources and two separate low impedance transformer coupled inputs with different step up ratios, providing 21 or 12dB gain.

The transformer inputs are meant to be used with low output impedance sources. Especially the yet to be planned and built all DHT phono stage. DHTs are known for their low gain, so any additional possibility to amplify the signal is needed for that.

All inputs, outputs and the power supply connector on the back side, along with a ground lift switch and separate ground connections to chassis and signal ground:

My apologies to Pieter and all who are waiting for my assessment of the sound of these new volume control transformers. I will report back as soon as the linestage is finished which will take a little more time. I hope you enjoy these photos in the meantime.

I quite like this new appearance and will adopt the same style to other components. The all DHT phono will have a similar look and I'm thinking about power amps in this style.

Of course the external power supply of this linestage will have a matching design, with caps, transformers and rectifiers on the top side.